Method for transferring heat



Nov. 8, 1932. J. F. WAIT METHOD FOR TRANSFERRING HEAT Filed June 13. 1930 iwf/.55.- MKM Patented Nov. d, ldd@ http@ earner trennten JUSTN F. WAIRIOF NEWAYR'E, N. Y., LSSGNQR TU SUN @EL GOM?, @El PHIADELPHI, PENNSYL'VNM, .d CRIPGRTIQN @ll NEW El ETHB FR TRANSFERRNG MAT .application tiled .lane le, 1930. Serlalv'lto. domata.

rlhis invention relates to an improved method and apparatus tor transferring heat trom a source to a point ot use, and particularly relates to an improved method and apparatus tor removing impurities trom a metallic medium such as mercury, cadmium, zinc, or the like, the vapors ot which are used to edect the heat transfer.

This application is a continuation in part y@ of my application Serial No. 48,987, -iiled naugust 8, 1925,which has matured into Patent No. 1,765,038, dated il une 17, 1930, in which is claimed the apparatus disclosed therein.

Heretotore the transfer oi heat through the medium oi metallic vapors has been accomplished by various methods and by the use ot various types of apparatus. ilev results ot substantial practical value have been obtained, such methods and apparatus as have been used have not proved entirely satisfactory and have been open to numerous objections, chiel among which are that the eilciency ot the metallic vapors is decreased by the presence oft entrained metal and that the low oi.i the vapors is retarded by the accumulations ol scale, oxide and other impurities present in the apparatus or carried into various parts thereolE by the vapors.

lt is the broad object oi the inventionto provide a method and apparatus for the utili- Zation otu metallic vapor as a heat transiter medium with maximum eciency and subject to proper control, and by which the vapors will be treed from entrained metal and from solid impurities, accumulation of which tends to retard the ilow of the vapors.

Having indicated in a general way the nature and purpose of the invention, l will now proceed to a detailed description thereof with reference to the accompanying drawing in which there is illustrated one form of apparatus which may be utilized for carrying out 45 the method embodying my invention, although it will be understood that the practiceo the method is not dependent upon the use of any particular form ot' apparatus.

ln the drawing the figure is a diagrammatic view of one form of apparatus constructed in accordance with the invention, certain parts thereot being shown in section.

The apparatus, all parts oit which are formed ol an onidizable metal such as iron, consists essentially ot a heating element comprising a chamber 2 `trom which depend hni gers d within which are located vertical tubular partition members 6, communication be tween the spaces inside and outside the tubular members being adorded by passages 8 at @w the bottoms thereof. rEhe heating element, or heater, is suitably mounted in brick vvorlr and is adapted to be heated by the application ot heat about hngers 4l. 'llhe heating element is charged with metal, as mercury, @5, cadmium, zinc, etc., or mixtures thereof, to the level indicated by the broken line l. Upon application ot heat, the metal circulates through the passages on the outside and inside ot members 6 to and from the chamber 70 2, the generated metallic vapors passing outwardly through pipe 10. 'lhe heated metal circulating to and from the chamber 2 passes downwardly and upwardly in the lingers at high velocity, which velocity decreases on the passage oit the metal into the chamber, thus permitting settling out and dotation ot solid impurities such as oxide, scale, etc., which may be mixed with the metal. .an aperture 13, provided with a suitable closure, a@

is formed in the end oi chamber 2 at a level permitting removal ot impurities trom the surface ot the metal in the chamber.

'lhe pipe 10, which leads from the top ot chamber 2 and which serves as a passage a5 for metallic vapors therefrom, is connected to a vapor dow cont-rol device which consists of a chamber 14 into which, from its `to the end portion l2 of pipe 10 projects. rom adjacentthe top of chamber 14 a pipe 16 oo leads to a. heat absorbing unit shown conventionally as a coil 18 located within a chamber 20 adapted to contain material to be heated which will absorb heat from the metallic vapors in the coil. From the bottom o: of the. chamber 14 av pipe 22 extends downwardly and upwardly, its end being connected to the bottom ot a second chamber 2l 'provided-with cooling fins 26. A pipe 27 joins the top of chamber 24 with a vacuum pump lo@ 29. A pipe 28 extending upwardly within chamber 24 connects it with a separator 30 theconstruction of which will be hereafter described. A connection 31 from the separator may be connected to a suitable pressure or vacuum producing device.

In the operation of the control device, the chamber 24 and pipe 22 are filled with a metal similar to that in the heating element, for example, mercury. rIhe level of the metal in the chamber is controlled by the pipe 28 which acts as an overow. The chamber 24 is positioned at a higher level than chamber 14 and the metal is prevented from iowing from chamber 24 to chamber 14 by maintaining a pressure in chamber 24 such that the liquid cannot rise in chamber 14 above the lower end of pipe 12. rIhe desired pressure is maintained in chamber 24 by means such as the pump 29 attached to pipe 27. So long as the metal in chamber 24 is prevented from flowing into chamber 14, vapors issuing from pipe 12 will pass from chamber 14 to the coil 18. rIhe vapors on entering l chamber 14 will lose velocity and any entrained metal will be dropped therein. If'

it is desired toshut off the iow of vaporsA from pipe 12, this is accomplished by varying the pressure on the metal in chamber 24 which will cause it to iow into chamber 14 and form a liquid seal over the end ot the pipe.

The metallic vapors which enter the heat exchange coil v18 are in part condensed therein and vapor and condensate tlow from the coil through a pipe 32 to a separator 34, the construction of which-will hereafter be described. An outlet 36 from the separator connects it with a condenser 38 from which condensate may flow through pipe 40 to another separator 42. 'Ihe separators 30, 34 and 42 are joined by pipes 44 and pipe 46 with the heatin element 2.

Joined to the eating element 2 by a pipe 48 is another separator 501 which is illustrated in section. This separator is similar to separators 30, 34, and 42 and will be described in detail, it being understood that the description applies to the other separators. The separator consists of a'chamber 50 surrounded by a trough 52 formed by an upturned flange into which the flange of a cover 54 extends, the last named flange extending into mercury 56 in the trough to form a liquid seal. The cover 54 is normally held in its closed position by means of a wedge orithe like whereby it may be removed for the purpose of cleaning the surface of the liquid metal in the separator. The separator receives liquidmetal through pipe 58 from condenser 60 which is arranged t0 receive vapors through pipe 62 from the safety chamber 64. This latter consists of a closed charnber provided with anv inlet pipe 68 communicating with pipe 10 and an overflow outlet Lesaase 70 which determines the normal level of liquid metal, as mercury, therein. Normally the liquid metal in the chamber 64 acts as a seal over the end of pipe 68 for normal pressures in the apparatus. It, however, the pressure becomes excessive, vapors will force through the liquid 66 and the pressure will be relieved. The vapors will be condensed in condenser 60 and the condensate, freed from impurities in the separator, returned to the heater.

In the operation of the device it will be noted that all liquid entering the heater 2 comes from a separator in which is retained the floating oxide or scale which accumulates. These impurities may beremoved from time to time by skimming them from the surface of the liquid in the separator.

The use of metallic vapors for purposes of heat exchange raises numerous difficulties due to several peculiar properties of the metallic media circulating in the systems in connection with the material and properties of the apparatus employed. While the 'following discussion is directed primarily' to mercury, simila'ractions and results occur in the cases of other metals such as cadmium, zinc, or the like.

In a system of the type described, and particularly a system subject to interrupted operation, air is present in variable quantities, being present either at the initiation of the process or accumulated by leakage during operation. One impurity which occurs is the loxide of the metal which is used as medium, in the case of mercury, mercuric or other oxide which forms under certain conditions and decomposes under others in various parts of the apparatus. 'A second source of impurities arises from the action of the hot active, monatomic, metallic vapors upon the materials of which the apparatus is constructed, generally fairly readily oxidizable metals Ysuch as iron. Apparently the mercury vapors, as well as the metal walls of the apparatus, at the high temperatures involved yield an electronic discharge which ionizes oxygen which thereby becomes sufficiently active to readily oxidize the metals of construetion. The reaction is relatively intense and positive under some conditions of operation and particularly when the system is held in imperfectly formed apparatus, under vacuum or when intermittent operation is involved or as When air is applied as at 72 to control the pressure. I do not wish to confine my claims to this exact explanation. The explanation offered is probably correct although subsequent scientific development may disclose other reasons for the results so far observed.

Simultaneously with the'above noted action of the mercury vapors oxygen enters through the pores of the metal,.providing a source whereby oxidation of the metals of raeaaaa it construction is edected. During the boiling of the mercury thereiis a thin` film of vapor between the metal and the liquid.

The oxidized products are continuously removed by bombardment of the heavy particles of mercury including those particles Which condense against the Wall of the structure. The high specific gravity of the mercury causes a very vigorous action on the apparatus because oi the high kinetic energy of the mercury due to its mass and monatomic form. rlhis action removes pieces ot scale, siliceous matter and even iron from the bombarded surfaces. A further corrosive action appears to result from the penetration ot portions ot the surfaces by the monatomic metallic vapors at high temperatures.

ln a metal vapor system, the edect of such impurities is very deleterious and their separation is a matter of diiiiculty. Apparently the solid impurities are highly dispersed and of a colloidal nature so that they are separated only vvith diculty While at the same time they collect in restricted passages so as to tightly plug the apparatus. By the use of the separator which is disclosed, by virtue of its design, there is obtained a definite motion of the minute particles of liquid mercury which coagulate into larger particles which separate out from the non-liquid oxide and subdivided mercuryparticles which doat. The described motion is primarily due to the mnetic energy oi the metallic vapors as they How from pipe 58 and impinge upon the surface of the liquid metal;

and is secondarily due to the surging ot the liquid during operation. The line 58 preferably enters chamber 50 tangentially so that flow ocondensate may give a small but etective centrifugal action which further assists in separation of the heavier mercury or other liquid metallic particles from the less heavy oxide and other impurities. rl`he drops ot mercury enter the separator at high velocity and these particles which have high density bombard the collected 'mass The motion and/or passage of drops through the mass causes continuous recovery of mercury admixed with oxides.

What l claim and desire to protect by Letters Patent is:

l. The method which includes vaporizing a metal, removing entrained liquid metal from the vapors, edectingcondensation of 'a part of the vapors by the absorption of heat therefrom, separating the condensate from the vapors and separating impurities from the condensate by dotation.

2.- The method which includes vaporizing a metal, removing entrained liquid metal rom'the vapors, eiecting condensation of a part ot the vapors bythe absorption of heat therefrom, separating the condensate from the remaining vapors, separating impurities trom the condensate by dotation, and returning the condensate to be vaporized.

3. rlhe process vvliich comprises heating a metallic liquid, forming monatomic gas, causing said gas to heat Walls of a container or said gas, condensing saidgas, causing con` densate to remove from said Walls oxidation products which may result from the contact ot gas with the Walls in the presence ot oxygen.

4. rllhe process which comprises forming vapors of a metal, condensing said vapors, collectingcondensate and oxide which may be produced by oxidation of the vapors, and separating condensate from oxide and again forming vapors there-from and withdrawing separated oxide from the system.

5. The method which includes vaporizing a metal to form monatomic vapors 1n an apparatus ot oxidizable material whereby oxidation of the apparatus may occur, removing entrained liquid metal trom the vapors, eftecting condensation of a art of the vapors by the absorption ot heat tberefrom, separating the condensate trom the vapors, and separating oxidation products from the condensate bydotation.

tl. rlhe method which includes vaporizing a metal to form monatornic vapors in an apparatus ot oxidizable material whereby oxidation of the apparatus may occur, removing entrained liquid metal from the vapors, et tecting condensation ot a part of the vapors by the absorption or heat therefrom, separating the condensate from the vapors, separating oxidation productsirom the condensate by dotation, condensing vapors separated trom the rst mentioned condensate, and separating oxidation products from the condensate ot the last mentioned vapors. I

7, The process which comprises icing metallic vapors, condensing said vapors, collecting such condensate and solid impurities within a separator, causing rotation ot the mass ot condensate and impurities and so separating .condensed metal from impurities.-

8; rlihe process which comprises heating 'a metallic liquid, forming monatomic gas, causing said gas to heat Walls ot a container ot said gas, condensing said gas, causing condensate to remove tromsaid vvalls oxidation products which may result from the contact ot gas with the walls. in the presence of oxygen, collecting said oxidation products and condensate at a surface of condensate and withdrawing portions of said oxidation products from said surface.

9. Theprocess which comprises heating a metallic liquid, forming monatomic gas, causing said gas to heat walls of 'a container of said gas, condensing said gas, causing condensate to remove from said walls oxidation products which may result from the contactv gen, collecting said ,oxidation products and condensate at a surface of condensate and withdrawing portions of said oxidation products from said surface and applying heat to condensate separated rom said oxidation products and forming monatomic gas therefrom.

10. The method which comprises forming metallic vapors, condensing said vapors, collecting condensed particles and oxidewhich may be produced by oxidation of the vapors on a surface of liquid metal, causing motion of said surface and so agglomerating condensed particles, and forming vapors therefrom.

11. The method which comprises forming metallic vapors, condensing said vapors, collecting condensed particles and oxide which may be produced by oxidation of the vapors on a surface of liquid metal, causing motion of said surface and so agglomerating condensed particles and forming vapors therefrom and withdrawing oxides.

In testimony of which invention, I have hereunto set my hand, at New York city, New York, on this 31st day of May, 1930.

JUSTIN F. WAIT. 

